More than 1000 juvenile fire-bellied toads have been released into the pond in Taarup Strand in Denmark

More than 1000 juvenile fire-bellied toads have been released into the pond in Taarup Strand in Denmark

The populations of fire-bellied toads in project areas of Denmark and Slovenia are very small. According to the monitoring, up to 5 calling males were heard in the Taarup Strand project area in Denmark and the Jovsi area in Slovenia.

Supportive breeding is one of the effective measures for the conservation of small fire-bellied toad populations on the verge of extinction because the survival rate of eggs and tadpoles is increased. For a successful rearing, we need to provide the eggs and tadpoles with conditions similar to those in their natural ponds. Aquatic plants that are placed into the outdoor breeding tanks have to be free of beetles, dragonfly larvae or other predators, and we have to ensure that birds like i.e. blackbirds and herons cannot predate the fire-bellied toad tadpoles.

It is estimated that in the natural situation, only 1 to 5% of eggs successfully develop into juvenile fire-bellied toads, which is too low for providing long-term survival of small populations. By hatching eggs in the rearing station, where the development to juvenile takes place, we prevent natural loss of amphibian offspring due to predators and other factors and consequently increase the survival rate to over 95%.

In the project area Taarup Strand in Denmark we have this year released more than 1000 juvenile fire-bellied toads into the nature. Tadpoles successfully developed during summer from eggs collected in the spring. When the tadpoles were medium sized, they were transferred from rearing pools to net cages in the ponds for completing their development to juvenile toadlets by feeding on epiphytic coverings of algae on the inner side walls of the net cages. The hard work of the Danish project team paid off when they successfully released metamorphosed juveniles from the net cages and they could spread out in the pond for the first time. In this way, we have significantly increased the number of juveniles, which we hope will survive as many as possible until adulthood, begin to reproduce and thus actively integrate into the existing population and strengthen it in numbers.

With the support of the Danish project partners, we will establish a rearing station Kozjansko Park in Slovenia where measures for population management of fire-bellied toads will take place. In the next few years, we will also improve and restore the aquatic and terrestrial habitats of the fire-bellied toad in the Jovsi project area. The implementation of all measures is crucial for ensuring stable fire-bellied toad population.

Photo: Niels Damm